Days dry can leave a lasting impact on the next generation, according to USDA data presented at the 2011 annual meeting of the American Dairy Science Association.
USDA researchers with the Animal Improvement Programs Laboratory in Beltsville, Md., examined U.S. Holstein records from 1997 through 2010 to investigate how dry period length affects calving ease, stillbirth rate and future development and survival of offspring.
Here are some of the researchers' findings:
Calving difficulty increased linearly as days dry increased, but leveled off at about 70 days dry.
Stillbirth rate was 4.15% for cows dry less than 30 days, 2.36% for cows dry 56-60 days and 3.33% for cows dry 91-120 days.
Heifers born to dams that were dry for either 56-60 days or 91-120 days were bred at 458 days of age compared to an age at first breeding of 463 days for heifers born to dams that were dry 0-30 days.
64.6% of heifers whose dams were dry less than 30 days survived to first calving. Survival was 70.1% for heifers whose dams were dry 56-60 days. Survival was 68.8% for heifers born to dams that were dry 91-120 days.
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